This study of Law School Admission Test (LSAT) performance by selected subgroups has been conducted to provide some baseline information that can later be referenced in a variety of projects and activities. The study provides a detailed psychometric analysis, by selected gender and ethnic subgroup membership, of LSAT Form OLSS1. This form was administered to approximately 42,000 test takers in September 1989. The data for these analyses are drawn from the test data of the first 95% of the answer sheets that were scanned and scored. Test performance is summarized as measured by total scaled LSAT score, section score, reliability, item difficulty, item discrimination, and response/omit patterns. Data are presented separately for males and females and for Asian American, Black/Afro-American, Caucasian, Hispanic, Mexican American, and Puerto Rican test takers. Overall, the data confirm the poorer performance of minority LSAT takers with compared with Caucasian test takes and confirm the fairly equal performance by male and female test takers. (Contains 23 tables and 9 figures.) (SLD)